PKCS7_decrypt - decrypt content from a PKCS#7 envelopedData structure

PKCS7_decrypt() must be passed the correct recipient key and certificate. It would be better if it could
       look up the correct key and certificate from a database.

       The lack of single pass processing and need to hold all data in memory as mentioned in PKCS7_sign() also
       applies to PKCS7_verify().

       Copyright 2002-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except in compliance
       with the License.  You can obtain a copy in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

3.5.0                                              2025-06-04                                PKCS7_DECRYPT(3SSL)

PKCS7_decrypt() extracts and decrypts the content from a PKCS#7 envelopedData structure. pkey is the
       private key of the recipient, cert is the recipients certificate, data is a BIO to write the content to
       and flags is an optional set of flags.

       PKCS7_decrypt - decrypt content from a PKCS#7 envelopedData structure

       Although the recipients certificate is not needed to decrypt the data it is needed to locate the
       appropriate (of possible several) recipients in the PKCS#7 structure.

       The following flags can be passed in the flags parameter.

       If the PKCS7_TEXT flag is set MIME headers for type text/plain are deleted from the content. If the
       content is not of type text/plain then an error is returned.

PKCS7_decrypt() returns either 1 for success or 0 for failure.  The error can be obtained from
       ERR_get_error(3)

ERR_get_error(3), PKCS7_encrypt(3)

        #include <openssl/pkcs7.h>

        int PKCS7_decrypt(PKCS7 *p7, EVP_PKEY *pkey, X509 *cert, BIO *data, int flags);